Means for receiving wired radio signals on space radioreceivers



Patented Jan. 3, 1933 UNITED STATES PATENT OFFICE ROBERT D. DUNCAN, JR., OF EAST ORANGE, NEW JERSEY, ASSIGNOR TO WIRED RADIO, INC., OF NEW YORK, N. Y., A CORPORATION OF DELAWARE MEANS FOR RECEIVING WIRED RADIO SIGNALS ON SPACE RADIORECEIVERS- Application filed June 3, 1931. Serial No. 541,770.

My invention pertains in general to electron discharge tube adapters and specifically relates to a combined tube adapter and wave filter system.

In my co-pending application Serial Number 431,116, filed February 25, 1930, and entitled Electron discharge tube adapter, I have disclosed a system for employing a space radio receiving system including the usual '10 space discharge detector tube with an adapter for use interposed between the detector tube and its supporting socket for tying in a wired radio tuning system so that either space radio or wired radio signals can be detected on the space radio detector tube and subsequently amplified on the space radio amplifier. It has been found, in such a system for tying in a source of wired radio signals to a space radio detector and amplifier, that the wired radio carrier frequency energy is sometimes present in the audio frequency amplifier, since the wired radio carrier frequencies are much lower than the space radio frequencies.

The presence of carrier in the audio system of the space radio receiver may cause distortion due to the saturation of the audio frequency iron core transformer.

One of the objects of my invention consists in providing means for eliminating carrier frequency oscillations in the audio frequency amplifying system in a combined wired radio and space radio receiving system.

Another object consists in producing a combined wired radio and space radio receiving system in which a low pass filter network is included in the detecting and audio frequency amplifying system.

Another object comprises providing an adapter for use interposed between a space discharge tube and a supporting socket therefor and which includes a filter network.

I accomplish the above desirable objects in a novel tube adapter having a low pass filter network incorporated therewith.

I In the drawing accompanying and forming a part of this specification and in which like reference numerals designate corresponding parts throughout:

Fig. 1 is a diagrammatic representation of 59 a space radio receiving system having an adapter for tying in a wired radio selective filter system to the detector and audio frequency amplifier; and

Fig. 2 is an elevation and partially sectioned View of the tube adapter and filter employed in my invention.

Referring to the drawing in detail and particularly to Fig. 1, power lines 1 convey both commercial power and carrier frequency energy. The lines 1 are indicative of a wired radio broadcasting system in which carrier frequency signals are impressed upon a power distribution network. A wired radio selective filter system 2 is connected to the lines 1 through capacitive couplings 3. The filter system 2 consists of a network for selecting desired frequency bands of carrier frequency energy.

A high frequency energy collecting system comprising an antenna 4 and ground connec tion 5 is connected to the input of a space radio tuning system 6. The space radio tuning system 6 comprises a suitable circuit for receiving high frequency signals of a desired frequency and may include space discharge tubes for radio frequency amplification. The output of the tuning system 6 is directed through a grid leak and condenser 7 to a supporting socket 8 adapted to hold a space discharge detector tube 9. The space discharge tube 9 is provided with the usual terminal pins 10 which will fit in corresponding terminal clips 11 in the socket 8. The terminal clip 11 which is associated with the plate or anode of the space discharge tube 9 is connected through an audio frequency transformer 12 to an audio frequency amplifier 13 and thence to any suitable translating device. A by-pass condenser 14 is provided across the primary of the transformer 12. The grid leak and condenser 7 is connected, as shown, to the terminal clip 11 which is associated with the grid or control electrode of the space discharge tube 9. The other terminal clips 11 which are associated with the cathode and heater filament of the space discharge tube 9 are connected, as indicated, to ground and to a source of electrical energy 25. A source of anode voltage 30 is provided, as shown, in circuit with the terminal clip 11 which is as- 100 'ceiving system.

sociated with the anode of the space discharge tube 9. The tuning system 6, grid leak and condenser 7, socket 8, space discharge detector tube 9, and audio frequency amplifier 1-3 comprise a typical space radio receiving system. In the normal use of such a system the space d scharge tube 9 would be inserted in the socket 8 and a suitable circuit thereby established between the output of the tuning system 6 and grid of the detector tube 9, and between the plate 01" the tube 9 and input of the audio amplifier 13.

However, it is especially desirable to provide means whereby wired radio signals can be made available on such a space radio re- To accomplish this, according to my invention, 1 provide a special type of adapter which is interposed between the space discharge detector tube 9 and support ing; socket 8 whereby the output of the wired radio filter system 2 can be conveniently tied into the detecting and. amplifying organization of the space radio receiver without disturbing the circuit constants of the space radio receiver. This adapter 15 is essentially of low capacitance construction and includes a plurality of terminal clips 16 which are similar to the termina clips 11 in the supporting socket 8. The adapter 15 also includes a plurality of terminal pins 17 which are similar to the terminal pins found on the space discharge detector tube 9. The terminal clips 16 are adapted to retain the terminal pins 10, while the terminal pins 17 are adapted to be inserted in the terminal pins 11 of the socket 8 in place of the space discharge detector tube 9.

A switch 18 is provided within the adapter for making connection with either of two terminals 19 or 20. The switch 18 is connected to the terminal pin 16 which is associated with the grid of the space discharge tube 9, while the terminal 20 is connected to the terminal pin 17 which is associated with the grid leak and condenser 7. The terminal 19 is connected through a grid leak and condenser 21 to the output of the wired radio filter system 2, the other side of which is grounded. The terminal pin 16 which is associated with the plate of the space discharge detector tube 9 is connected through inductance 22 to the terminal pin 17 which is associated with the audio fraquency trans former 12. The inductance 22 is connected in parallel with two series connected capacitances 28 and 2st. The caoacitances 28 and 2 1 and the inductance 22 together comprise afilter network of the cut-oi? type which is adapted to attenuate all frequencies lying above a certain predetermined frequency value. This predetern'iined frequency value, in the present embodiment of my invention, is just below the lowest carrier frequency to be demodulated, whereby all carrier frequency energy will be attenuated by the network 22-23-2 l. A connection is provided between the two capacitanccs 23 and 24 to the terminal pin 17 and clip 16 associated with the grounded cathode the space discharge detector tube 9. The terminal clips 16 associated with the heater filament of the space discharge tube 9 are connected to corresponding terminal pins 17 and fit into the terminal clips 11 connected to the source of electrical energy 25.

The mechanical construction of the adapter 15 will be apparent by reference to Fig. 2. It will seen that the terminal clips 16 are mounted upon an insulating" disk 26 having holes therein for receiving the terminal pins 10 of the space discharge detector tube 9. 26 is disposed within a tubular Another insulating disk 28 is prothin the tubular shield 27 and supe rminal pins 17.

wi; r the terminal clips 11 in The inductan e 22 is mounted 2S ad'iacent the capaciatinc; d;- and 24. The switch 18 is also "races 23 inounteo upon th disk 28 and provided with a handle which extends through an aperture in he tubule =hield 27. A

19 can he moved to render the detector tube 9 ell ec'tive receiving signals from ei er space raeic tuning: system 6. It wi l be obvious that the output from the plate of the detector tube 9 will be restricted to the dcsired audio frequencies due to the presence oi the low pass filter system in the adapter This filter s em will prevent the carency current, such as received by stem 2. from entering the prii'nary stormer 12.

cllicient method tor employing; a source of wired radio ials with a space radio receiving? ystem and at the same time overcoming the introduction of disturbing; wired radio carrier frequencies in the space radio audio frequency anization. It will be obvious my 'iveution possesses connncrcial utility and offers many adn its By the use of my system no. t ce radio receiving system by tying in space radio signals without producing accompanying: disturhingr effects in the space radio detector and receiving system. AL though I have shown a preferred embodiment of my invention I do not wish to be limited thereto except insofar as may be pointed out in the appended claims.

i i lat I claim as new and original and desire to secure by Letters Patent of the United States is:

1. A radio receiving system, comprising, a space radio energy collecting system, a wired radio energy collecting system, a detector tube, a. supporting socket for said detector The terminal the wired radio filter system 2 or' em or" my invention provides an le to increase the usefulness of a tube, an audio frequency amplifier operatively connected to said socket, an adapter inter posed between said detector tube and said socket, a single pole two position switch in said adapter for connecting said detector tube to said space radio energy collecting system or said Wired radio energy collecting system and a filter system included in said adapter for excluding super-audible frequencies from said amplifier.

2. In a combined space and wired radio receiving system, a space radio tuning system,

a wired radio tuning system, a detector tube common to said tuning systems, an audio frequency amplifier common to said detector, a socket for said detector tube and an adapter interposed between said detector tube and said socket containing a single pole two-position switch for connecting said detector tube with either said wired radio tuning system or said space radio tuning system selectively and a filter system in said adapter for attenuating super-audible frequencies and preventing such frequencies from entering said audio frequency amplifier.

3. A combined space and wired radio receiver comprising a space radio tuning system, a wired radio tuning system, a thermionic detector tube common to said tuning systems, a socket therefor, an audio frequency amplifier operatively connected to said socket and an adapter interposed between said socket and said detector tube and containing a single pole two-position switch for connecting said wired radio tuning system or said space radio tuning system to the grid of said detector tube and a filter system included in said adapter for preventing super-audible frequencies from entering said audio amplifier.

ROBERT D. DUN CAN, JR. 

